RAPID: Microbial cycling of Iron and Sulfur in Spring Creek Reservoir, Iron Mountain Mine

2018年7月，卡尔大火烧毁了近23万英亩的土地，包括铁山超级基金遗址周围的地区，在那里，受矿山影响的排水被转移到斯普林克里克水库。微生物改变了水库中水和沉积物的化学成分，并改变了流向下游的水质。今年，雨季落在烧伤疤痕上的雨水预计会导致快速侵蚀，并将额外的沉积物沉积到湖中。该项目将研究受污染的沉积物如何沉积在湖泊中，以及微生物如何转化沉积物、孔隙水和水库水。项目人员将检查流入的沉积物、沉积物中的微生物群落，以及2018/2019季节风暴事件后水库的水质。结果将显示微生物活动如何改变斯普林克里克水库的沉积物化学和水质，并为类似的烧毁地区和矿井影响的土壤提供见解。美国西部的采矿活动导致数千英里的溪流受到酸性矿山排放的影响，并造成矿山和冶炼厂作业对土壤的广泛污染。从历史上看，铁山煤矿排放的受污染的水和沉积物对萨克拉门托河上游造成了影响，萨克拉门托河是重要的饮用水源和鲑鱼产卵流。该项目的结果将有助于矿山管理人员、地方和区域环境规划人员以及水库管理人员了解再动员沉积物的运动和命运，并规划野火对有助于稳定受污染土壤的植被和复垦基础设施的影响。铁山超级基金遗址包含几个废弃矿山的残留物，Spring Creek在进入Keswick水库和萨克拉门托河之前通过Spring Creek碎屑坝和水库（SCR）捕获排放。2018年7月，卡尔大火烧毁了斯普林克里克流域的大部分地区，因此，预计2018/19年雨季的沉积物将很高。沉积物的涌入为研究微生物群落如何在酸性矿井排水影响的湖泊中定植和改变沉积物和孔隙水提供了机会。先前的SCR研究表明，在高储层水位时，微生物群落会减少孔隙水中的铁和硫酸盐，而在低水位时，铁和硫化物会氧化，产生酸性并动员金属。拟议的研究将描述沉积物流入，微生物群落如何在新沉积物中发展，以及微生物活动如何改变孔隙水化学。研究小组将于2018年11月至2019年期间对沉积物、孔隙和地表水进行8次采样和分析。分析将包括矿物学；铁、硫、氧和水的pH值；以及微生物群落的分子分析。本研究将为酸性矿山排水污染环境的环境生物地球化学研究提供基础知识，并为SCR水质管理提供指导。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

In July 2018, the Carr Fire burned nearly 230,000 acres, including the area surrounding the Iron Mountain Superfund Site where mine-impacted drainage is diverted into the Spring Creek Reservoir. Microbes alter the water and sediment chemistry in the reservoir and change the quality of the water flowing downstream. This year, rain falling on the burn scar during the wet season is expected to cause rapid erosion and deposit extra sediment into the lake. This project will investigate how contaminated sediments are deposited in the lakes, and how microbes transform sediment, pore water, and reservoir water. Project personnel will examine inflowing sediments, microbial communities from the sediment, as well as water quality in the reservoir following storm events in the 2018/2019 season. Results will show how microbial activity changes sediment chemistry and water quality in the Spring Creek Reservoir and provide insights into similar burned over areas and mine-impacted soils. Mining activities in the Western USA has resulted in thousands of miles of streams impacted by acid mine discharge, and widespread contamination of soils by mine and smelter operations. Discharge of contaminated water and sediment from the Iron Mountain mine has historically impacted the upper Sacramento River, an important drinking water source and salmon spawning stream. The results of this project will help mine managers, local and regional environmental planners and reservoir managers understand the movement and fate of remobilized sediments, and to plan for the effects of wildfire on the vegetation and reclamation infrastructure that help to stabilize contaminated soils. The Iron Mountain Superfund Site contains the remnants of several abandoned mines, and Spring Creek drains part of this area with the Spring Creek Debris Dam and reservoir (SCR) capturing discharge before it enters the Keswick Reservoir and Sacramento River. In July 2018, the Carr Fire burned most of the Spring Creek watershed, and thus, sedimentation is expected to be high during the 2018/19 rainy season. The influx of sediment provides an opportunity to investigate how microbial communities colonize and transform sediment and pore waters in an acid mine drainage-influenced lake. Prior research in the SCR suggests that microbial communities reduce iron and sulfate in pore waters during high reservoir levels, and that iron and sulfide oxidize when water levels are low, producing acidity and mobilizing metals. The proposed research will characterize sediment influx, how microbial communities develop within the new sediment, and how microbial activity changes pore water chemistry. The research team will sample and analyze the sediments and pore and surface water 8 times from November 2018 to 2019. Analyses will include mineralogy; iron, sulfur, oxygen, and pH of the water; and molecular analyses of the microbial communities. This research will provide fundamental insights into environmental biogeochemistry in acid mine drainage-contaminated environments and provide guidance for managing the water quality in the SCR.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.